U.S. Pat. No. 3,587,138 (Inventor: Bammert et al; Assignee: Schloemann, Germany) discloses a mold-closing device that includes a four-column hydraulic press usable in an injection-molding machine, in which a movable mold-carrying plate is slidable along a column of the press and is also releasably lockable on the column.
U.S. Pat. No. 5,853,773 (Inventor: Choi; Assignee: Husky Injection Molding Systems Limited, Canada) discloses a system and a process for controlling mold activity of a molding machine by using a clamping device for positioning a movable-mold platen on a carrier device for engaging the movable-mold platen with another platen, and for sustaining forceful engagement of the movable-mold platen with the another platen and the carrier device, and for breaking the movable-platen from the another platen and the carrying device. The movable-mold platen includes a movable-mold half and the another platen includes another mold half. Also disclosed is a way for determining an adjustable starting position of the clamping device and the movable-mold platen. Also disclosed is a way for achieving greater accuracy of an adjustable starting position for the clamping device and the movable platen. The way for adjusting the starting position includes a mechanism for actuating the clamping device. Also disclosed is a device for monitoring and controlling the position of the clamping device and the movable platen. Also disclosed is a mechanism for sustaining the clamp-up force at a prescribed level.
U.S. Pat. No. 5,922,372 (Reissued as U.S. Pat. No. RE. 37,827; Inventor: Schad; Assignee: Husky Injection Molding Systems Limited, Canada) discloses a clamping system for use with platens of a molding machine. The molding machine includes a stationary platen having a first mold half affixed thereto and also includes a movable platen having a second mold half affixed thereto. The movable platen travels along a plurality of tie bars and reciprocatively moves between a mold-open position and mold-closed position. The clamping system is used for applying a clamping force to the movable platen.
U.S. Pat. No. 6,468,449 (Inventor: Fujikawa; Assignee: Sodick Company Limited, Japan) discloses an injection molding machine that includes a mold-clamping device. The mold-clamping device includes an electromechanical mold opening and closing mechanism, a hydraulic mold clamping mechanism, and a mold thickness adjustment device. The mold thickness adjustment device includes a first-detection device for detecting the position of a mold-clamping ram, a second-detection device for optically detecting the position of a half nut device, and a mold clamping ram position control device for hydraulically holding and controlling the position of the mold-clamping ram. The position of the half nut device is held by hydraulic control at the mold thickness adjustment position during mold opening and closing. In a mold opening and closing operation, the mold-clamping ram exerts a large mold opening force that is used to open the mold.
U.S. Pat. No. 5,753,153 (Inventor: Choi; Assignee: Husky Injection Molding Systems Limited, Canada) discloses a control system for clamp-up and mold break operations of tie bar clamping mechanisms, the control system determines and adjusts starting position of securing/clamping mechanism and movable mold after each molding operation to achieve greater accuracy. In a particular embodiment of the securing/clamping assemblies, the securing/clamping assembly is mounted on the outwardly facing side of movable end platen and within a bore. In order for the securing/clamping assembly of the platen to function with the tie bar, the tie bar includes an elongated end section having a plurality of spaced protrusions in the form of teeth separated by longitudinally extending inner slots. Accordingly, at the end of tie bar is a toothed outer surface. The toothed outer surface of tie bar is in the form of longitudinal outer strips of teeth extending in the axial direction of the tie bar, wherein the teeth are preferably aligned in a radial direction on the tie bar and separated by a space in the axial direction. Each of the strips of teeth such as strips of teeth is radially separated from another strip of teeth via an outer axially extending slot, such as slots. Outer strips of teeth and slots of tie bar are adapted to engage and align, respectively, with inner teeth and grooves of securing/clamping assembly in order to cause a locking engagement with the bar.
FIG. 1A is a perspective view of a known clamp assembly 100 (hereafter referred to as the “clamp assembly 100”) as depicted in FIG. 3 of U.S. Pat. No. 5,922,372. The clamp assembly is sometimes referred to as a pineapple-type clamp because of its teeth arrangement.
FIG. 1B is a cross-sectional view along a longitudinal axis of the clamp assembly of FIG. 1A. The clamp assembly is used in a molding system 102. The clamp assembly is depicted in a mold-opened position. The molding system 102 includes a base 104. A stationary platen 106 is fixedly attached to the base 104. A movable platen 108 is transversally slidabe along the base 104. A stationary mold half 110 is fixedly attached to the stationary platen 106. A movable mold half 112 is fixedly attached to the movable platen 108. The mold halves 110, 112 cooperatively define a mold cavity therebetween for molding an article therein. An actuator 130 is activated to translate or stroke the movable platen 108 toward and away from the stationary platen 106 (so as to open and close the mold halves 110, 112 relative to each other). The actuator 130 includes a column 141 which is attached to the movable platen 108. Once the mold halves 110, 112 are closed against each other, the clamp assembly is actuated to apply a clamping force to the mold halves 110, 112 while the injection unit 114 injects a molding material into the mold cavity. The clamping force keeps the mold halves 110, 112 together while the molding material enters the mold cavity under pressure. Once the molding material has solidified in the mold cavity, the clamp assembly removes the clamping force and then it actuates to apply a mold-break force that is used to separate the mold halves 110, 112 apart from each other so that the molded article may then be removed from the mold halves 110, 112. Then once the mold halves 110, 112 are broken apart, the actuator 130 actuates to move (or stroke) the platens 106, 108 apart from each other.
The clamp assembly includes a clamp ram 116 and a clamp piston 118. The clamp ram 116 is attached to the column 141. The clamp ram 116 includes an inter-meshable structure 120. The clamp piston 118 includes an inter-meshable structure 142 (structure 142 is not depicted in FIG. 1B but it is depicted in FIG. 1D). The inter-meshable structures 120, 142 intermesh relative to each other between an unmeshed position and an inter-meshed position. FIG. 1B depicts the clamp ram 116 and the clamp piston 118 in the unmeshed position. Sometimes the inter-meshable structures 120, 142 are referred to as “pineapple” structures.
The actuator 130 (which is sometimes referred to as a “stroke cylinder”) is used to actuatably move the column 141 which then, in turn, moves the movable platen 108 to open (or separate) the mold halves 110, 112 or to close the mold halves 110, 112 relative to each other. The actuator 130 includes a rod 132 and a cylinder head 134 disposed within a chamber 136 defined by the column 141. Defined by the chamber 136 and the cylinder head 134 are a mold-opened hydraulic column 138 and a mold-closed hydraulic column 140. The actuator 130 is actuated to close the mold halves 110, 112. Preferably, the actuator 130 is slowed down just before the mold halves 110, 112 make contact with each other to ensure that the mold halves 110, 112 do not inter-collide (this is sometimes referred to as a mold-protect phase).
A housing 122 houses the clamp piston 118, and the clamp piston 118 moves relative to the housing 122. Sometimes the housing 122 is referred to as a clamp block. One way to accommodate molds of varying sizes and/or shapes is to have the housing 122 translate along the base 104 and then locking the housing 122 into a fixed position to the base 104. A clamping-hydraulic column 124 and a mold-break hydraulic column 126 are defined between the clamp piston 118 and the housing 122. An actuator 128 is attached to the housing 122 and to the clamp piston 118. The actuator 128 is used to rotate the clamp piston 118 so that the inter-meshable structure (structure 142) associated with the clamp piston 118 may inter-mesh or unmesh relative to the inter-meshable structure 120 of the clamp piston 116. It is understood that FIG. 1B shows the clamp assembly in an un-actuated condition (that is, the assembly is not yet actuated to apply a force (either clamping force or mold-break force) that is transferred over to the mold halves 110, 112).
FIG. 1C is a cross-sectional view of the clamp assembly of FIG. 1B in which the mold halves 110, 112 are positioned in the mold-closed position. The mold-closed hydraulic column 140 of the actuator 130 is energized to push the column 141 against the movable platen 108 and in response the movable platen 108 moves toward the stationary platen 106 and thus the mold halves 110, 112 are closed against each other. It is understood that FIG. 1C shows the clamp assembly in an un-actuated condition (that is, the assembly is not yet actuated to apply a force that is transferred over to the mold halves 110, 112).
FIG. 1D is a cross-sectional view of the clamp assembly of FIG. 1B in which the clamp assembly is placed in a clamp-intermeshed position. The clamp piston 118 includes an inter-meshable structure 142 that is rotated into the intermeshed position relative to the inter-meshable structure 120 of the clamp ram 116. The actuator 128 was actuated to rotate the inter-meshable structure 142 into this position. This phase of operation is called a clamp lock-up phase. It is understood that FIG. 1D shows the clamp assembly in an un-actuated condition (that is, the assembly is not yet actuated to apply a force that is transferred over to the mold halves 110, 112).
FIG. 1E is cross-sectional views of the clamp assembly 100 of FIG. 1B at subsequent phases of the clamping cycle. It is understood that FIG. 1D shows the clamp assembly in an actuated condition (that is, the assembly is actuated to apply a force that is transferred over to the mold halves 110, 112).
The upper-left corner of FIG. 1E shows the clamp assembly in a clamp-up phase (that is, the clamp assembly is actuated to apply a clamping force to the mold halves 110, 112). The clamping-hydraulic column 124 includes hydraulic oil. The clamping-hydraulic column 124 is actuated to push the piston 118 toward the mold halves 110, 112 (by having a pump device pump the hydraulic oil into the column 124). In turn, teeth of the inter-meshable structure 142 are urged to contact and then to push against the teeth of the inter-meshable structure 120. The inter-meshable 142 includes a rear-tooth portion 144 and a flank-tooth portion 146. The inter-meshable 120 includes a rear-tooth portion 148 and a flank-tooth portion 150. The clamp piston 118 pushes the flank-tooth portion 146 against the flank-tooth portion 150 and in this manner a clamping force is transferred from the clamp piston 118 over to the clamp ram 116. In turn, the clamp ram 116 transfers the clamping force over to the column 141 and then onto the mold halves 110, 112.
The upper-right corner of FIG. 1E shows the clamp assembly in a mold-break phase (that is, the clamp assembly is actuated to apply a mold break force to the mold halves 110, 112). The clamping-hydraulic column 124 is de-actuated so that the clamp piston 118 no longer applies the clamping force over to the clamp ram 116. The mold-break hydraulic column 126 is actuated so that the clamp piston 118 and the inter-meshable structure 142 are moved so that the rear-tooth portions 148, 144 of the inter-meshable structures 120, 142 contact one another. The mold-break hydraulic column 126 is further actuated to push the clamp piston 118 against the clamp ram 116 so that the mold halves 110, 112 are urged to break open (that is, the clamp piston 118 has applied the mold break force to the mold halves 110, 112). Once broken open, the actuator 130 cannot yet be actuated to move the movable mold half 112 away from the mold half 110 because the teeth of the inter-meshable structures 120, 142 are intermeshed with each other.
The lower-left corner of FIG. 1E shows the clamp assembly in a clamp un-mesh phase (or clamp-unlock phase). The clamping-hydraulic column 124 is actuated to translate the teeth structures away from each other (this is a teeth clearance phase). Once the teeth are clear from each other (that is, the teeth are offset from each other), the actuator 128 may then be actuated to rotate the clamp piston 118 so that the inter-meshable structures 120, 142 no longer inter-mesh with each other.
The lower-right corner of FIG. 1E shows the clamp assembly (in an un-meshed condition) in a mold-open phase (that is the clamp assembly is de-actuated to apply no forces to the mold halves 110, 112). The actuator 128 was actuated to rotate the clamp piston 118 so that the inter-meshable structures 120, 142 no longer inter-mesh with each other. The actuator 130 is then actuated to translate the column 141 and thus move (stroke) the movable platen 108 so as the mold half 112 becomes separated from the mold half 110.